Dolby Atmos for sound bar applications June 2018 1 Since its introduction in the movie theatre in 2012, Dolby Atmos® has revolutionized cinema sound and reinvigorated home entertainment. Dolby Atmos introduces the concept of object-based audio, in which sounds are represented as individual objects that can be located anywhere within the space above and around the listener. With Dolby Atmos tools, content creators can precisely place and move sounds anywhere in your living room, including overhead, to make entertainment incredibly immersive and lifelike. Dolby Atmos and audio objects Dolby Atmos in the home is an object-based audio format with the capability to reproduce up to 128 simultaneous objects that may be present in the original cinematic mix. Every sound in a scene — a mosquito buzzing, a helicopter taking off, a car horn blaring — can be represented as a separate audio object that can be positioned and moved throughout the three-dimensional space. The car speeds from left to right; police officers search the upstairs floor, walking back and forth; the hawk swoops through the woods, clipping tree limbs as it flaps its wings to gain altitude. Using sophisticated content creation tools that represent the audio objects in a three-dimensional space, filmmakers can isolate each audio object in a scene and decide exactly where they want it to be and how they want it to move. In the final sound mix, the audio objects are combined with positional metadata — data that describes each audio object, including its location, its size or intensity, and its movement. Figure 1. Filmmakers can use this Dolby Atmos tool to position and direct audio objects throughout the three-dimensional space. 2 In playback systems in the cinema as well as in the home, the Dolby Atmos object audio renderer is the intelligence that directs the system. Informed of the speaker count, the type of speaker, and the location of the speaker, the Dolby Atmos object audio renderer decodes the positional object metadata, then scales and adapts the Dolby Atmos soundtrack in real time for optimal playback, based entirely on the defined capabilities of the playback system. A key benefit of the Dolby Atmos object audio renderer is its ability to scale a soundtrack to different room sizes and speaker configurations, providing an optimum presentation of the original soundtrack in each listening environment. Dolby Atmos in content today Major Hollywood studios and studios worldwide are partnering with Dolby to create Dolby Atmos cinematic presentations. A substantial portion of feature films created today use the Dolby Atmos format. In North America alone, Dolby Atmos has debuted in the home on Blu-ray Disc™ and Ultra HD Blu-ray™ Disc with the support of home video companies, including Paramount, Warner Bros., Universal, Lionsgate, Fox Pictures, and Sony Pictures Entertainment, and more announcements are scheduled. In addition, Dolby Atmos content is being created in Japan, China, India, France, Spain, Germany, and the United Kingdom. Dolby Atmos is also supported by streamed media (over the top [OTT]), as well as by broadcast providers in North America, China, and France, with more announcements in the near future. Furthermore, Dolby is working with artists, mixers, and music producers to bring the Dolby Atmos experience to homes worldwide. Additionally, game developers are integrating object-based Dolby Atmos compatibility, with games already on the market and more on the way. In PC systems and in gaming consoles, playback of video games through a Dolby Atmos system heightens the “wow” factor, bringing gamers a new level of reality and total immersion in the game environment. Compatibility Dolby Atmos content is fully playback-compatible with most home theater systems. Dolby Atmos audio tracks will play on any conventional channel-based system that support Dolby® TrueHD (Blu-ray Disc) or Dolby Digital Plus™ (streaming media) and will deliver traditional 5.1 or 7.1 sound, depending on the system configuration. Content providers benefit from not having to maintain separate Dolby Atmos mixes, and consumers don’t have to worry about the new Dolby Atmos mixes playing on their older systems. Because of the freedom that Dolby Atmos provides for mixers to position audio objects in the score, consumers with traditional systems often comment that they enjoy a more intense movie experience from their channel-based systems during playback of a content encoded with a Dolby Atmos soundtrack. 3 Bringing Dolby Atmos to the home theater The unique scalability of Dolby Atmos object-based audio enables a highly compelling and immersive listening experience from a variety of playback platforms and speaker layouts. With support for as many as 34 discrete speakers, the scalability of Dolby Atmos enables a virtually unlimited number of playback and speaker configurations in the home theater. Today, a home theater enthusiast can choose to integrate from as few as eight speakers up to and including 34 speakers in a reference playback system. In fact, Dolby Atmos supports more than 30,000 possible speaker positions within the home theater. Dolby Atmos debuted in the home theater in 2014, first introduced in audio/video receivers (AVRs), preprocessors, Dolby Atmos enabled speakers, and home-theater-in-a-box (HTIB) systems. Supported speaker configurations include 5.1.2 and from 5.1.4 up to and including 7.1.4. (Note: the first digit refers to the number of traditional listener-level surround speakers, the second digit refers to the number of subwoofers, and the final digit refers to the number of overhead speakers in the Dolby Atmos setup.) The scalability of Dolby Atmos also enables even more “lifestyle-friendly” speaker configurations, including sound bar products. Dolby Atmos in lifestyle-entertainment solutions When high-definition television (HDTV) on flat-panel displays was introduced, manufacturers promoted sound bar products as a solution to improve the audio so that it matched the quality of the video. As display products became thinner, on-board speakers became smaller, and the sound of the television set was compromised to become nearly unlistenable. The construct of a sound bar could match that of the display product and fit unobtrusively into most households — a major consideration for the marketplace. Unfortunately, most of these products merely replace the sound missing from the on-board television sets, and most devices do not deliver the degree of quality and immersion that a multispeaker home entertainment system provides. More advanced sound bars have come to market equipped with next-generation decoders (for Dolby Digital Plus and/or Dolby TrueHD) and sophisticated virtualization techniques to provide a deeper sense of immersion than is available from traditional 2.0- or 2.1-equipped sound bars. With a wide variety of form factors, prices, and designs, the sound bar is the fastest-growing area in home entertainment today. This space is ripe for invention and innovation for consumers who demand more entertainment value and quality from their playback investment. The unique scalability of Dolby Atmos allowed Dolby engineers and researchers to rethink the sound bar as a platform for delivering a high-quality immersive audio experience. Years of research and testing have resulted in a package of interoperable components designed to deliver a highly immersive listening experience from object-based audio and channel-based content — all from the form factor and convenience of a sound bar. The result is a highly versatile entertainment solution that can fit into a wide variety of lifestyles and environments. 4 The importance of overhead sound In real life, sounds come from all around us, including overhead. Having the ability to re-create overhead sounds is a key element in making Dolby Atmos sound so realistic. If we see a helicopter take off onscreen and then hear its blades cutting through the air above our heads, the experience makes us feel like we’re really in the scene, not just watching it. Dolby Atmos cinemas re-create these overhead sounds with an array of overhead speakers above the audience. But this is impractical in most home entertainment applications. In sound bar applications, Dolby has two different approaches to delivering height effects. These different approaches yield a variety of product options and prices points for consumers. Sound bars with Dolby Atmos upward-firing elements Through our knowledge of psychoacoustics and sound physics, Dolby has developed technologies that create overhead sound from speakers that are located only a few feet off the floor. Dolby Atmos enabled speakers fire sound upward, where it reflects off the ceiling to accurately reproduce overhead sound. This technology has been further refined for integration into sound bar products that produce the Dolby Atmos experience. Figure 2. Dolby Atmos enabled speakers reflect sound off the ceiling to produce an incredibly lifelike overhead sound. The Dolby Atmos enabled speakers are enclosed in a sealed baffle within the sound bar cabinet. During construction of the sound bar, careful attention is given to avoid horizontal diffusion of sound intended for overhead effects; the use of a specialized pinna filter in the sound bar further amplifies the perception of overhead sound originating from the Dolby Atmos enabled speaker elements. The ideal ceiling height for Dolby Atmos enabled speakers is between 7.5 and 12 feet (2.3 and 3.7 meters). However, testing at Dolby confirms that listeners can achieve a high-quality overhead experience from Dolby Atmos enabled speakers in environments where the ceiling height ranges up to 14 feet (4.3 meters). In fact, the system is so robust that recessed lighting fixtures, chandeliers, crown molding, and heating or air conditioning vents in the ceiling do not noticeably interfere with the Dolby Atmos experience. 5 Dolby Atmos sound bars with height virtualization Dolby Atmos height virtualization processing leverages Dolby’s deep understanding of human audio perception to simulate an immersive audio experience while using fewer speakers.